Tuesday, 15 October 2013

Summary: Aquaponic system bio-filter crash
likely caused by chloramine poisoning of bacteria, which then led to buildup of
high levels of ammonia. Subsequent treatments to reduce ammonia in the system
ultimately proved ineffective. Follow us through our trials and tribulations as
we tried to avert an aquaponist’s nightmare scenario.

Chapter
1: System Crisis, Ammonia Bailout

Approximately a week later, results from a
water test sent a cold chill to our heart. The unassuming water sample became a
dark, dark green within a matter of seconds—the colour of ammonia levels of 8ppm
and/or beyond. Further chemical tests revealed nitrites were ~0ppm but the
system’s pH had climbed rapidly towards 7.1. These were the telltale signs of
dissimilation, the conversion of nitrates back to ammonia through the nitrogen
cycle, or worse, a total wipe out of all the beneficial bacteria, the Nitrosomonas and Nitrospira that convert the ammonia to nitrites and nitrites to
nitrates respectively. With such a grim diagnosis, treatment was immediate: an
emergency water change with the water in our reservoir.

High levels of chlorines and chloramines in the water killed off a significant level of bacteria in the system.

Discharge water and replace with dechlorinated water.

Continued high levels of chlorines and chlroamines in the water is detrimental to the Nitrosomonas'growth. Without Nitrosomonas the only other way to reduce ammonia levels biologically is via plant roots. However, our fish would produce ammonia at a higher rate than our plants could absorb. Without intervention, ammonia levels will increase until the system fails completely.

More than likely. In fact Vancouver municipal water supplies contain chlroamines. The water had sat for a while and the water's chlorine tends to burn pretty rapidly in the presence of air. Chlroamines on the other hand last much longer in the water and have a half- life of ~23 days and do not "burn out" like chlrorine. In which case, rapid addition of dechlroaminators is required to chemically convert chlroamine into less harmful substances.

Water reserves contain high levels of chlroines and chlroamines, both substances are known to be bactericidal. Adding this water to the system will kill the beneficial bacteria.

Treat water with dechlorinators and dechloraminators and let the water sit for a couple days. Then do a water change.

Without dechlorination, the new water will not contribute to the health and growth of the Nitrosomonas that metabolize ammonia. This leads to the same problem mentioned above.

More than likely. In fact Vancouver municipal water supplies contain chlroamines. The water had sat for a while and the water's chlorine tends to burn pretty rapidly in the presence of air. Chlroamines on the other hand last much longer in the water and have a half- life of ~23 days and do not "burn out" like chlrorine. In which case, rapid addition of dechlroaminators is required to chemically convert chlroamine into less harmful substances.

Dead zones created by roots and decaying biomatter created anaerobic zones that in turn lead to dissimilation.

Clear and clean all possible dead zones.

The bacteria in the nitrogen cycle produce nitrates, a key ingredient for plant foliage growth, from ammonia only in sufficiently oxygenated water. When the aerobic conditions cease, the bacteria will stop producing nitrates and instead "reverse" the nitrogen cycle that will lead to a buildup of ammonia in the system.

Less likely because the system had the same or higher amount biomatter previously and the system did not experience high levels of ammonia. Furthermore, oxygen levels did not drop significantly throughout the crisis.

Extensions to the system contained substances that killed beneficial bacteria.

Wash out the new additions and/or remove new extensions.

New extensions and products in the past have been advertised as "chemically inert" or "pH neutral" are sometimes not. Given insufficient new leads, every correlation was treated as a possible causation.

Not likely. After washing the extensions with water, chemical test on the "wash" water did not yield evidence of toxic substances, e.g. ammonia and nitrites.

Failure in machines, e.g. water pumps and oxygenators, led to impeded water circulation resulting in high levels of ammonia.

Locate all mechanical failures and either repair, maintain, or replace all failure points in the system.

All machines have a lifespan and will fail at different times. When a machine has failed the water is no longer being circulated and the fish waste, i.e. ammonia, is not being delivered to the plants for absorption leading to an accumulation of ammonia in the fish tank.

Not likely because both the plant bed and fish tank experienced high levels of ammonia; thus, the water had circulated from the fish tank to the plant bed. Intermittent mechanical failures due to power outages were also unlikely because all electronic sensors were operational throughout the whole incident.

Due to our preparation, we felt reassured that we had nipped the problem on the bud…